1) Tom Hanks is an American actor and filmmaker known for his versatile performances in films such as "Forrest Gump," "Saving Private Ryan," and "Cast Away." He has received numerous awards, including Academy Awards, Golden Globes, and BAFTAs.

2) The largest living structure on Earth is the Great Barrier Reef, spanning over 2,300 kilometers (1,400 miles) along the coast of Australia.

3) The development of blockchain technology, first introduced in 2008 with the creation of Bitcoin, has enabled secure and decentralized digital transactions and led to the emergence of cryptocurrencies.

4) The United Nations (UN) is an international organization founded in 1945 with the goal of promoting peace, security, and cooperation among nations through diplomatic and political means.